This application is based on patent application Ser. No. 10-140268 (1998) filed May 21, 1998 in Japan, the content of which is incorporated hereinto by reference.
1. Field of the Invention
The invention relates to an ink printing method and an ink-jet printing apparatus, and specifically to an ink-printing method and an ink-jet printing apparatus for performing printing by using a processing liquid which make a coloring material in an ink insoluble.
2. Description of the Prior Art
As an ink-jet printer or the like come into widespread use, such devices are required to perform printing with higher quality as one of tendencies in such devices. It is well known that one of important factors to determine such print quality is an optical density (hereinafter simply called xe2x80x9cODxe2x80x9d) which is measured as that of an ink dot or a set 0xc3xa ink dots formed printing medium. For example, when printing a character such as a letter of black, in general, the higher the OD of the dots formed with a black ink on a printing medium is, the higher contrast the printed characters provide to a color of a field of the printing medium, and this improves the printing in quality. Moreover, in other colors, for example, also in dots of cyan, magenta, or yellow, the higher ODs of these colors are, the clearer printed images are.
One of factors upon which an OD of a dot formed with the ink on the printing medium depend is an amount of a coloring material of the ink which does not penetrate into the printing medium but remains on a surface thereof. From this point of view, it is well known to increase an amount per se of ink ejected by a print head. As an easier method, for example, it is widely performed to scan the print head plural times for ejecting the ink plural times on a same point to increase an ink quantity to be given onto the printing medium.
As other method of allowing a large amount of the coloring material remain on a printing medium, there has been recently provided a method in which a processing liquid which makes the coloring material insoluble is applied onto the printing medium together with the ink and thereby the coloring material is made remain more to improve the density.
From this point of view, the assignee of this application provides a printing apparatus and a printing method disclosed in Japanese Patent Application Laying-open No. 8-281930 (281930/96). Here, for a print area of black, a black ink is ejected and the processing liquid is also ejected in a predetermined pattern of pixels. Moreover, this processing liquid also functions as cyan ink which is made cationic to be oppositely polarized to anionic black ink. Thus, it is possible to obtain the above-mentioned effect of increasing the density by making the coloring material in the black ink insoluble. Further, the increase in the optical density is aimed at while preventing color tone from deviating by performing printing in other colors in a pattern simultaneously.
Moreover, according to the invention described in the above-mentioned gazette, a print head provided for the processing liquid is not required. Also, it is possible with a simple configuration to achieve the effects such as an improvement in water resistance and prevention from feathering and bleeding by use of the processing liquid, in addition to improvement of print quality due to increasing in the density.
A similar art disclosed in a gazette of EP A 831135 with respect to European Patent Application is also known. The gazette discloses that a light color ink, which is low concentration ink of magenta or cyan, is applied to the printing medium in an overlaying manner with the black ink and the light color ink is made have property that insolubilizes the black ink.
However, in any of the methods described above of increasing the density, it may occur that printing quality is degraded due to a deviation of respective dots of ink from each other. This deviation of dots occur when plural times of ink ejection are performed to overlay dots, or when a dot of the black ink and the cyan ink or the light color ink, which functions as the processing liquid, are overlaid.
For example, in the case that a serial type print head is used for printing, ejection position may become uneven among multiple-time scanning of the print head for ejecting ink multiple times on a same position, due to uneven motions of a carriage. Thus, the above-mentioned deviation of ink dots upon overlaying them.
Moreover. even when using, what is called, a full line type print head which is fixedly used on a printing apparatus, it may happen that a plurality of heads are not in normal positional relation to each other. Thus the ejection positions between. for example, the black ink and the cyan ink functioning as the processing liquid, which are ejected from the plurality of heads are made to deviate. Especially, this full line type print head is of a long-size for arranging relatively large amount of ejection orifices which are arranged in extent corresponding to a width of printing paper fed for printing. Therefore, the deviation may sometimes extend to that equivalent to about a few pixels which are arranged in 600 dpi. Furthermore, it is not easy to register positions of the ejection orifices among the plurality of heads for decrease the above-mentioned deviation. Moreover, a variation in accuracy of feeding the printing medium also may cause the above-mentioned deviation of the ink dots in overlaying them.
Furthermore, the above deviation may be caused also when there are variations in the direction of ejected ink between the print heads. For example, in case that some of the corresponding ejection orifices of the respective heads for ejecting inks at a same position are deflected in the ejecting directions, the ink or the ink equivalent to the processing liquids from that ejection orifices are not ejected at the position to be originally targeted on. Thus, the deviation is caused in overlaying them.
As mentioned above, if the deviation of ink dots is caused when plural inks are ejected one upon another or ink and a colored processing liquid (the processing liquid functioning as an ink for printing) for making the ink insoluble is ejected in a overlaying manner for aiming at an increase in OD, the deviation becomes noticeable due to the difference between hues of the dots. As a result of this, the print quality is degraded.
Especially, since structures employing the color ink making the black ink insoluble, which are disclosed in the above-mentioned two gazettes, do not take into consideration of a relation between the difference between hues of inks which are deviated from each other and the degradation of print quality owing to such difference of the hues, the deviation and the difference of hue interact with each other so that the print quality is more seriously degraded.
It has been proposed to improve an accuracy of head mounting or paper feeding. However, it sometimes brings about such problems as an increase in the device cost or complexity in adjustment procedures, etc.
The objects of the present invention is to provide an ink print method and an ink-jet printing apparatus which can achieve an improvement in print quality beginning with an increase in density of printed image while permitting the deviation even if it is caused in overlaying of ink dots owing to the above-described various factors.
The applicant of the present invention has achieved this invention by paying attention to and examining a relation between a mutual deviation value between plural ink dots and a relative density in a range in which this deviation does not have a significant influence on the print quality.
Another object of the present invention is to provide an ink print method and an inkjet printing apparatus in which, in a case of forming an image of a black series, a low concentration colored ink having an opposite polarity to that of a black series ink is added thereto in an overlaying manner, the deviation can be made visually unrecognized for the low concentration of the colored ink even if the overlaid condition of inks is not within a predetermined range, and in addition to an increase in density due to insolubility of the black series ink, the increase in the density of the black image within a range in which no change is recognized in the hue.
In the first aspect of the present invention, there is provided an ink printing method comprising the steps of:
employing a black series ink and a low concentration colored ink which has a lower concentration than a colored ink with higher lightness than that of the black series ink, has a same series of color as that of the colored ink and has a polarity different from the black series ink; and
forming an image of a black series by at least a partly making the black series ink react with the low concentration colored ink.
In the second aspect of the present invention, there is provided an ink printing method comprising the steps of:
employing a black series ink, one of or a plurality of colored inks having higher lightness than the a black series ink and a low concentration colored ink which has a lower concentration than the colored ink, has a same type of color as that of the colored ink and has a partly different from that of the black series ink; and
forming an image of a black series by at least partly making the black series ink react with the low concentration colored ink.
In the third aspect of the present invention, there is provided an ink printing method comprising the steps of:
employing, a plurality of colored inks different from a black series ink and having higher lightness than that of the black series ink, and a low concentration colored ink having a lower concentration than that of the colored ink and a different polarity from that of the colored ink; and
forming an image of a color by at least partly making the colored ink react with the low concentration ink.
In the fourth aspect of the present invention, there is provided an ink-jet printing apparatus for performing printing by means of ink ejection parts respectively ejecting a black series ink, and a low concentration colored ink which has a lower concentration than a colored ink with higher lightness than that of the black series ink, has a same series of color as that of the colored ink and has a polarity different from the black series ink,
wherein an image of a black series is formed by at least partly making the black series ink react with the low concentration colored ink.
In the fifth aspect of the present invention, there is provided an ink-jet printing apparatus for performing printing by means of ink ejection parts respectively ejecting a black series ink, one of or a plurality of colored inks having higher lightness than the a black series ink and a low concentration colored ink which has a lower concentration than the colored ink, has a same series of color as that of the colored ink and has a polarity different from that of the a black series ink
wherein an image of a black series is formed by at least partly making the black series ink react with the low concentration colored ink.
In the sixth aspect of the present invention, there is provided an ink-jet printing apparatus for performing printing by means of ink ejection parts respectively ejecting a plurality of colored inks different from the a black series ink and having higher lightness than that of the black series ink, and a low concentration colored ink having a lower concentration than that of the colored ink and a different polarity from that of the colored ink,
wherein a colored image is formed by at least partly making the colored ink react with the low concentration colored ink.
In the seventh aspect of the present invention, there is provided a low concentration colored ink which is employed together with a black series ink and one or a plurality of colored inks having higher lightness than the black series ink in a printing apparatus, has lower concentration than the colored ink and has a same series color as the colored ink,
wherein the low concentration colored ink has opposite polarity to at least the black series ink to have a function of making the black ink insoluble.
In the eighth aspect of the present invention, there is provided an ink set comprising:
a black series ink; and
a low concentration ink which has lower concentration than a colored ink having higher lightness than the black series ink, has a same type color as the colored ink, and has an opposite polarity to the black series ink to have a function of making the black series ink insoluble.
In the ninth aspect of the present invention, there is provided an ink set comprising:
a cyan ink; and
a low concentration cyan ink having an opposite polarity to a black series ink to have a function making the black ink insoluble and having lower concentration than the cyan ink.
In the tenth aspect of the present invention, there is provided an ink set comprising:
a black series ink;
a yellow ink;
a magenta ink;
a cyan ink; and
a low concentration cyan ink having a function making at least the black series ink insoluble and having lower concentration than the cyan ink.
In the eleventh aspect of the present invention, there is provided an ink manufacturing method of manufacturing a low concentration colored ink which is employed together with a black series ink and one or a plurality of colored inks having higher lightness than the black series ink in a printing apparatus, has lower concentration than the colored ink and has a same series color as the colored ink has, the method comprising the steps of:
providing a coloring material for the low concentration colored ink having an opposite polarity to the black series ink to have function making the black ink insoluble; and
adding a solvent to the coloring material to manufacture the low concentration colored ink.
In the twelfth aspect of the present invention, there is provided a rubbing resistance improving method used when performing printing with a black series ink and a low concentration colored ink having lower concentration than a colored ink which has higher lightness than the black series ink, having a same series color as the colored ink and having a function making the black series ink insoluble, the method comprising the steps of:
ejecting the black series ink; and
ejecting the low concentration ink on the black concentration ink after ejection of the black series ink.
In the thirteenth aspect of the present invention, there is provided an ink ejection data generation method comprising the steps of:
providing ejection data for a black series ink; and
generating ejection data for a low concentration colored ink having lower concentration than a colored ink which has higher lightness than the black series ink, having a same series color as the colored ink and having a function making the black series ink insoluble, so that a dot pattern is formed on a printing medium in a pattern according to a predetermined algorithm, on a dot pattern of the black series ink formed based on the ejection data for the black series ink.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.